Perforated pipe and apparatus, system and method for perforating a pipe

ABSTRACT

A pipe and system for forming perforations in a pipe are provided. The pipe is for a well bore for filtering materials transported through the pipe and comprises: a wall having an exterior surface and an interior surface, the wall forming the pipe and shaped in a cylinder; and a perforation located in the wall, the perforation for receiving sediment in the materials and forming an aperture in the wall from the exterior surface to the interior surface with a first opening on the exterior surface having a first dimension across a first major axis of the first opening and a second opening on the interior surface having a second dimension across a second major axis of the second opening. The first opening is shaped to be either round, oval, elliptical or racetrack.

FIELD OF DISCLOSURE

The disclosure describes generally a perforated pipe and an apparatus and a method for perforating a pipe to form at least one perforation therein. In one application, the pipe is for use in the production of oil from formations that contain heavy oil or tar sands.

BACKGROUND OF DISCLOSURE

In tar sands and heavy oil recovery, a pipe, being a casing, tubing or other liner, is typically installed in a well bore for production of oil from an underground formation or producing zone. The pipe is preferably perforated or slotted with multiple longitudinal slots about its circumference before placement in the well bore. The pipe may be referred to as a slotted liner. A desired length and width of the slots perforated in the pipe and a desired number of slots depend upon various factors, including the granular size of any sand in the formation, the minimum strength and integrity of the pipe required for the particular application or use of the pipe and the rate of the oil/sand influx into the pipe.

In existing pipes, the slots have been narrow enough to prevent significant amounts of formation materials from entering and clogging up the well and associated equipment such as pumps. For wells installed in formations containing fine-grained materials, liner slot width may need to be as narrow as approximately 1.0 millimeter (0.04 inches) or even considerably less. The slots have been long enough and numerous enough to allow for effective flow into the liner from outside of the liner, without reducing the liner's structural strength below safe levels. The slots may be of any convenient length, but they are typically in the range of approximately 75 mm to 100 mm (3 to 4 inches) long. They are usually arrayed at uniform spacing about the circumference of the pipe, at radial intervals as low as 5 degrees. They are commonly cut into the liner sidewall using narrow circular slitting blades. One method uses a “gang mill” fitted with multiple slitting blades radially oriented on planes passing through the longitudinal axis of the liner. As the liner is moved longitudinally relative to the gang mill, the blades are deployed so as to cut slots of desired length through the liner sidewall. The liner's structural strength (especially its flexural strength) is particularly important for horizontal wells, in which the liner must retain sufficient strength to be bent through transition sections between vertical and horizontal well bores without fracture or excessive plastic deformation.

The slots have been straight or keystone. A straight slot has the same slot width on the inside and outside diameter of the pipe. A straight slot is used when sand control is not a major concern or the sand granular size is relatively large. A keystone slot may be rectangular in shape and have a larger width slot on the inside diameter (ID) than on the outside diameter (OD) of the pipe. A keystone slot may be used when plugging of the slot from sand is a concern. The OD of the slot screens the sand granular size permitted to enter the pipe, while the larger ID permits the sand to pass from the slot into the pipe. Typically slots and keystone slots are formed by cutting into the pipe using a saw with a circular blade. Existing slot forming techniques may create serrations on the profile wall of the cut slot that allow sand and in situ particles to hang and build on these edges. Current slot forming techniques and slot formations may overly weaken the strength of the pipe.

There is therefore a need in the industry for a pipe and a method of manufacturing same that addresses deficiencies in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a perspective view of a section of a pipe having a series of conical perforations formed therein according to an embodiment;

FIG. 2 is a schematic diagram of an end view of the pipe having the series of conical perforations formed therein of FIG. 1 according to an embodiment;

FIG. 3A is a schematic diagram of a side internal view of a section of the pipe of one of the conical perforations formed therein of FIG. 1 according to an embodiment;

FIG. 3B is a schematic diagram of side cross-section view of the section of the pipe of FIG. 3A according to an embodiment;

FIG. 3C is a schematic diagram of a side internal view of another section of the pipe having another conical perforation formed therein of FIG. 1 according to an embodiment;

FIG. 3D is a schematic diagram of side cross-section view of the section of the pipe of FIG. 3C according to an embodiment;

FIG. 3E is a schematic diagram of a side internal view of yet another section of the pipe having still another form of a perforation formed therein of FIG. 1 according to an embodiment;

FIG. 3F is a schematic diagram of side cross-section view of the section of the pipe of FIG. 3E according to an embodiment;

FIG. 4A is a schematic diagram of a water jet or laser or other similar system for forming a series of conical perforations in the pipe of FIG. 1 according to an embodiment;

FIG. 4B is a schematic diagram of an end view of part of the water jet or laser or other system of FIG. 4A forming a conical perforation in the pipe of FIG. 1 according to an embodiment;

FIG. 4C is a schematic diagram of an alternative end view of part of the water jet system of FIG. 4A forming a conical perforation in the pipe of FIG. 1 according to an embodiment;

FIG. 5A is a schematic diagram of a perspective view of a section of a second pipe having a series of differently sized conical perforations formed therein according to an embodiment;

FIG. 5B is a schematic diagram of a perspective view of a section of a third pipe having a series of conical perforations and rectangular slots formed therein according to an embodiment;

FIG. 5C is a schematic diagram of a perspective view of a section of a fourth pipe having a series of conical perforations and rectangular slots in a staggered offset configuration formed therein according to an embodiment;

FIG. 5D is a schematic diagram of a perspective view of a section of a fifth pipe having a series of conical perforations formed therein following an arcuate path along the pipe according to an embodiment; and

FIG. 5E is a schematic diagram of a perspective view of a section of a sixth pipe having an arcuate perforation formed therein following a thread pattern of the pipe according to an embodiment.

DESCRIPTION OF EMBODIMENTS

Exemplary details of embodiments are provided herein. The description that follows and the embodiments described therein are provided by way of illustration of an example or examples of particular embodiments of principles of the present disclosure. These examples are provided for the purposes of explanation and not limitation of those principles and of the disclosure. In the description that follows like parts are marked throughout the specification and the drawings with the same respective reference numerals.

Briefly, an embodiment provides a pipe (or slotted liner) having differently shaped perforations formed therein and systems, methods, processes and devices to manufacture same. The present disclosure relates to a perforated pipe and an apparatus and a method for perforating a casing or pipe.

In a first aspect, a pipe for a well bore for filtering materials entering the pipe is provided. The pipe comprises: a wall having an exterior surface and an interior surface, the wall forming the pipe and shaped in a cylinder; and a perforation located in the wall, the perforation for receiving and screening the materials and forming an aperture in the wall from the exterior surface to the interior surface with a first opening on the exterior surface having a first dimension across a first major axis of the first opening and a second opening on the interior surface having a second dimension across a second major axis of the second opening. In the pipe, the first opening is shaped to be either round, oval, elliptical or racetrack.

In the pipe, the first opening may be round in shape; the second opening may be round in shape; and the first major axis may be smaller than the second major axis.

In the pipe, the perforation may be a truncated right cone in shape.

In the pipe, the perforation may be a truncated oblique cone in shape.

In the pipe, an axis for the truncated oblique cone may be offset in a direction of expected flow for the pipe.

In the pipe, an axis for the truncated oblique cone may be offset oblique to a direction of expected flow of the materials in the pipe.

In the pipe, the first opening may be round in shape; the second opening may be round in shape; and the first major axis may be larger than the second major axis.

The pipe may further comprise a second perforation located in the wall, where the second perforation forms a second aperture in the wall from the exterior surface to the interior surface with a third opening on the exterior surface having a third dimension across a third major axis of the third opening and a fourth opening on the interior surface having a fourth dimension across a fourth major axis of the fourth opening. In the pipe at least one of the third or fourth dimensions may be different from the corresponding first or second dimensions.

In the pipe, the second perforation may be located in a line of a direction of flow of the materials in the pipe with the perforation.

In the pipe, the second perforation may be located in offset from a line of a direction of flow of the materials in the pipe with the perforation.

In the pipe the third dimension of the second perforation may be larger than the first dimension of the perforation.

In the pipe the third dimension of the second perforation may be smaller than the first dimension of the perforation.

The pipe may further comprise a slot located in the wall, where the slot is in proximity to the perforation at a location in the pipe that is in a direction of flow of the materials in the pipe.

In the pipe, edges of an interior opening of the slot may be rounded by a water jet.

In the pipe, the wall may be shaped in a cylinder.

In the pipe, the perforation may be formed by a water jet applied to the exterior surface of the pipe; and a sacrificial pipe may be placed in the interior of the pipe as the water jet forms the perforation.

In other aspects, various combinations of sets and subsets of the above aspects are provided.

Now general features of an embodiment are described. Referring to FIGS. 1-3B, aspects of an embodiment of the disclosure for a pipe are shown.

FIG. 1 shows a section of pipe 100, which is generally cylindrical, having exterior surface 102 and interior surface 104. Between exterior surface 102 and the proximate interior surface 104 is wall 106. Pipe 100 may be of any length, diameter and thickness. An exemplary length for pipe 100 in a well bore is in the range of approximately 3 m long (approx. 9.8 feet) or less to approximately 15 m long (approx. 49.2 feet) or more. A plurality of perforations 108 are provided along the length of pipe 100, where the perforations are located on exterior surface 102 and extended through wall 106 to interior surface 104. It can be seen in one configuration of perforations 108 that openings for perforations 108 located on interior surface 102 are generally larger than their corresponding opening on surface 104. As shown, in one configuration, perforations 108 are of similar size (on the exterior and interior surfaces 102 and 104) and are formed in lines running along the traverse axis of pipe 100. In a typical well bore installation, materials located on the outside of pipe 100 are received into pipe 100 via the perforations. The materials entering pipe 100 are screened by the size and shapes of the perforations. Further details on the forming of perforations 108 are provided later in this disclosure. In an alternative configuration, materials may be injected into the interior of pipe 100 at one end of pipe 100 (e.g. at a derrick) and some of these materials may flow outside of pipe 100 through perforations 108 into the well bore.

Pipe 100 may be inserted into a well bore in the ground having a generally vertical section, connected to a heel portion, connected to a generally horizontal portion having a toe portion (not shown). A typical location is either in a vertical section or a horizontal section of the well bore. In other embodiments, pipe 100 may be located in other environments (e.g. in water or another liquid, in air, in a particulate environment (e.g. a grain hopper), etc.). Pipe 100 is generally cylindrical, but may have in any part any cross-section shape (e.g. square, rectangular, oval, hexagonal, polygon, etc.) having a wall that defines an interior space on one side and an exterior space on another side of the wall. The wall may be closed onto itself (e.g. as a cylinder) or not (e.g. as a trough).

FIG. 2 shows a cross-section end view of pipe 100 of FIG. 1, showing additional features for perforations 108. FIGS. 3A and 3B show a close-up of a section of pipe 100 and one perforation 108 of pipe 100 of FIG. 1, where perforation 108 takes the shape of a truncated part of a right (circular) cone, so that the centers of openings 110 and 112 are aligned to the normal of wall 106. FIGS. 3C and 3D show a close-up of another section of pipe 100 and another perforation 108′ of pipe 100 of an embodiment, having a slanted conical shape (as a truncated oblique cone) where the centers of the openings 110′ and 112 are offset from each other to the normal of wall 106, taking the shape of a truncated part of the oblique (circular) cone. The offset may be provided on multiple axis (e.g. on the longitudinal axis and the traverse axis). This configuration may be useful in reducing drag in flows carried by pipe 100. The orientation of perforation 108′ in pipe 100 may be aligned such that its axis (generally passing through or near the center of both the ID and OD) is offset to face, not face, be transverse to or be oblique to the direction of expected flow of materials in pipe 100. The slanted cone may be inverted with the OD being larger than the ID. FIGS. 3E and 3F show a close-up of another section of pipe 100 and another perforation 108″ of pipe 100 of an embodiment, having a slanted perforation where the centers of the openings 110″ and 112 are offset from each other to the normal of wall 106, and where opening 110″ is a different shape (here generally oval) compared to the shape of opening 112. It will be appreciated that shapes of openings 110″ and 112 may be separately configured to other shapes, sizes and orientations in other embodiments. The features of pipe 100 shown in FIGS. 1, 2 and 3A-3F are not to scale. Per FIG. 2, in one embodiment, a pattern for a plurality of perforations 108 in pipe 100 is a set of eight (8) lines of perforations, each line running along the longitudinal axis of pipe 100 and each line being spaced approximately equidistant from each other. In other embodiments, more or less lines of perforations 108 (e.g. 1, 2-7, 9, 10 or more etc.) can be provided on pipe 100. The lines of perforations may not be symmetric or equidistant from each other. The lines may be spaced at regular radial intervals (e.g. as close as every five degrees—for a total of approximately 72 lines or more around pipe 100). The alignment of the perforations in the lines may be offset from each other. Axis lines 114 show the center along longitudinal and medial axis for pipe 100.

Perforations 108 are shown having an exterior opening 110 (as provided on exterior surface 102) and an interior opening 112 (as provided on interior surface 104). For one configuration of perforations 108, they are generally conical with a round OD and ID and where their exterior openings 110 are smaller than their interior opening 112. For one embodiment, the size of interior opening 112 is dependent on the size of the exterior opening 110 (as an offset size of the exterior opening). For illustration, six of the eight perforations 108 have an OD that is smaller than their ID and two of the eight perforations 108 have an OD that is larger than their ID. As such, perforation 108 b is an exemplary “inverted” perforation that has its opening 110B (as an OD) that is larger than its opening 112B (as an ID). As such, a cutting head may be positioned so that it cuts an outline for opening 110 with a first lateral offset (e.g. the cutting head set to be a distance from its target cutting point on pipe 100 and a second angular offset aiming the cutting head to be directed towards it center point by a value (e.g. a distance or a number of degrees) to create interior walls 116 of perforation 108 in wall 104. As such, wall 116 would have an inwardly angled side. In one embodiment, the angular offset θ of wall 116 (measured from the plane of surface 102 to the radial axis of pipe 100) is between approximately 1 and 15 degrees, such as 6 degrees. Negative degree offsets from an axis may be provided (for example when scribing a perforation having an OD is larger than the ID). In one embodiment, opening 110 may have an OD of approximately 0.025 mm (0.010 inches) with an ID set to be on a line that approximately 6 degrees away from the center line of its perforation. The size of the ID, in such an offset design, will depend on the thickness of wall 106. Alternatively, specific sizes for ODs and IDs may be set and walls 116 may then be accordingly defined. Different sizes of ODs and Ds openings may be provided depending on dimensions of pipe 100 (such as its OD, ID and/or thickness of wall 106), the composition of pipe 100, the field of use of pipe 100, the reservoir type, sand type and composition, produced or injected fluids and others.

For an embodiment a perforation that is not slotted and/or not formed by a circular blade as described herein provides benefits over slots formed in existing slotted liners.

First, geometrically, a conical perforation with a circular opening tends to be a stronger form than other forms (e.g. a rectangular shaped opening). This geometric strength may tend to increase an overall strength of a liner of pipe 100 for downhole installation and thermal loading on pipe 100, while having minimal impact on inflow performance of pipe 100. Notably, as a circular opening lacks a corner, the shape resists inducing flow stresses that may be present in a slot having a distinct corner (e.g. in existing keystone slots). This configuration may allow higher installation loads and thermal loads without permanent deformation or potential for localized strains and allows for equalized distribution of stresses within pipe 100.

Also, relatively small aperture openings compared to similarly dimensioned rectangular slots for a liner may be manufactured or machined into pipe 100. The OD opening may be the size of a nozzle aperture for a cutting head in a water jet or laser cutting system.

Also, high open areas in pipe 100 may be manufactured without compromising comparable structural integrity of a liner as a lower open area perforated liner due to the overall structural strength difference between the conical perforation and the longitudinal perforation. This may assist in controlling fluid velocity and flow rate to perforation 108 (known as skin factor due to flow convergence) and drag forces on particles within this near well bore region and further assists in reducing pressure drops that are generally associated with higher flow rates.

It is noted that a profile of conical perforation 108 may demonstrate vertical or near-vertical striations (if any striations are present) instead of circular or arc-length striations in current perforated liner perforations. This at least near vertical striation may reduce a possibility that in situ particles during the downhole application build on the striations as the particles are in line with a flow direction of fluids along pipe 100 instead of being perpendicular to the flow, as is with existing slotted liners.

A conical perforation may also create a spherical conglomeration of in situ sand particles around its OD opening, thereby assisting in creating a stable arching of sand above and around the conical perforation, which may be more difficult to disaggregate with fluctuating flowing and operating conditions than with the arches that form around the longitudinal perforation using slotted liner geometries. The arching of the in situ particles around a perforation form beneficial filtering and stabilization of sand around the perforation so that very little in situ particles fall onto or into the perforation during production, except when fluctuating production rates or operating conditions change so that the stable arches de-stabilize and flow into or onto the perforation and then new in situ particles may form another stable arch over the perforation after this flushing event.

Pipe 100 with conical perforations 108 may be advantageously used in sites for thermal exploitation projects, such as steam assisted gravity drainage (SAGD) projects and cyclic steam stimulation (CSS) projects as this will provide the necessary aperture openings for sand control and the open area for flow as well as strength for installation and thermal loading during steam injection and hot production operations of SAGD and CSS applications.

In other configurations for perforations 108, shapes of openings 110 and 112 may each be different (e.g. oval, triangular, square, rectangular, pentagonal, hexagonal, polygonal, etc.) and may each have different sizes (e.g. the same size, opening 112 being smaller than opening 110, etc.). It will be appreciated that geometric shapes formed on pipe 100 may not have perfect geometries: for example, a round opening may not be a perfect circle, an oval may include rounded corners (like a racetrack), an ellipse may have a blunted side and a square may not have four exactly equally sized sides. A given perforation 108 may not be symmetrical along its length and may have an irregular shape and varying dimensions for any one of its opening 110, opening 112 and/or at part of its wall 116. For example, perforation 108 be mostly conical but may have a flattened side. As such, for a non-circular opening, the terms OD, ID and “diameter” (interior and exterior) may be used to refer to one or more dimensions across major and/or minor axes or a cross-sectional dimension for its openings. In such configurations, a major axis can be considered to be the longest dimension of the opening and a minor axis can be considered to be perpendicular to the major axis. As such, the term major axis for an opening is used herein to describe generally a longest (or most significant) dimension across the opening and includes a diameter of a circular opening and a major axis of an oval or elliptical opening. Exemplary sets of sizes of ODs for exterior openings 110 to IDs for interior openings 112 are approximately: 0.26 mm for an OD and 0.51 mm for a corresponding ID (0.01 inches for an OD and 0.02 inches for the corresponding ID); and 0.31 mm for an OD and 0.56 mm for a corresponding ID (0.012 inches for an OD and 0.022 inches for the corresponding ID). Alternatively or additionally, sizes for an OD and an ID can be expressed as a simply difference in size. For example, the OD of opening 110 may be set to be smaller (or larger) that the ID of opening 112 by a specific size (e.g. 0.01 mm, 0.015 mm, 0.02 mm, etc.—corresponding to 0.004 inches, 0.006 inches, 0.008 inches, etc.). It will be appreciated that other sizes and relative sizes can be provided for one or more dimensions of opening 110 and 112.

Shapes described herein for an embodiment may provide additional rigidity to pipe 100 and may assist with filtering properties, having regard to expected flow rates and materials being carried in pipe 100 at a given site. These shapes may provide beneficial flow characteristics to the slot/perforation or sand control. These shapes may have good divergent flow characteristics to the perforation and through the perforation.

Pipe 100 may be made of any material, such as an alloy of steel, which may be hardened and pipe 100 may be for any industrial, commercial or residential purpose. In one embodiment, pipe 100 is an oil country tubular goods (OCTG) pipe, which is typically manufactured in one of several methods, such as:

-   -   a continuous mandrel-rolling process and a push bench process         for a pipe having an OD (at its major axis) from approximately         between 21 mm (approximately 0.8 inch) and 178 mm (approximately         7 inches);     -   a plug mill rolling process for a pipe having an OD (at its         major axis) of approximately between 140 mm (approximately 0.8         inch) and 178 mm (approximately 7 inches); or     -   a cross-roll piercing and pilger rolling process for a pipe         having an OD (at its major axis) of approximately between 250 mm         (approximately 0.8 inch) and 178 mm (approximately 7 inches).         Such pipes are frequently used in high-stress environments and         are typically exposed to simultaneous stresses from, for         example, torque by drilling, axial tension from dead weight of         the pipe itself and internal pressure from excavation of         drilling fluid from the inside of the pipe. Heat treating the         pipe may be used to strengthen the pipe. An alloy, including a         corrosion resistant alloy (CRA) for a pipe typically contains         chromium and magnesium. In other embodiments a pipe may be made         of plastic or thermoplastic material, concrete, ceramic or other         materials known to a person of skill in the art.

With some configurations and dimensions of a pipe with perforations recited for an embodiment, details of a system, method and apparatus for forming perforations, such as perforations 108 (FIG. 1) in a pipe according to an embodiment are now provided.

While it is possible to cast a pipe with perforations formed during casting, an embodiment generally forms one of more of perforations on a finished pipe. Perforations 108 may be excised, punched, drilled, sandblasted or otherwise cut from pipe 100. Exemplary cutting technologies include a water jet cutting system, a plasma torch, a laser, drilling using drill bits and others. In one embodiment, a rig is provided to cut perforations 108 in pipe 100 on site where pipe 100 is about to be laid. As such, forming perforations 108 in pipe 100 provides a drilled hole in pipe 100, while retaining benefits of a seamed or keystone perforation, which provides sand control and anti-plugging characteristics to the perforation through larger ID aperture opening-to-OD aperture opening and divergent flow characteristics to the perforation.

FIG. 4A shows features of an exemplary system 400 for forming perforations 108 in pipe 100. System 400 comprises pipe transport system 402 for pipe 100 and cutting system 404. In one embodiment cutting system 404 is a water jet cutting system, where head 406 is positionable about transport system 402 and pipe 100. Head 406 provides a nozzle from which a high pressure stream of water (or other liquid) is sprayed as stream 408, cutting through whatever is located beneath (such as pipe 100). Reservoir 410 contains a water supply for head 406. Reservoir 410 may include a tank, a flow metering system and shields. Reservoir 410 may contain water or water mixed with an abrasive and/or a coolant. For cutting soft materials, water may be used. An abrasive may be added to cut stronger or harder materials; exemplary abrasives include garnet, aluminum oxide and silicon carbide. Depending on material characteristics of pipe 100, generally materials that may be cut fully with a water jet may have a thickness of between approximately 0.64 mm to 760 mm (0.025 and to 30 inches). Pump and control module 412 provides mechanical, computer and control systems to regulate the water flow through head 406 and to locate head 406 at a specific location about transport system 402 and pipe 100 (e.g. at a specific height above a specific location on pipe 100 and at a specific angle relative to the designated center of pipe 100). Head 402 may be held at its set position while transport system 402 moves pipe 100 and/or head 402 may move in concert with movement of transport system 402. Typically, an orifice opening on head 402 for stream 408 has a diameter of between approximately 0.08 mm (0.003 inches) and 0.6 mm (0.023 inches). Pump and control module 412 may include a pump, a pressure intensifier and one or more tanks.

Head 406 is mounted or supported upon a movable frame (not shown) in a manner and by any mechanism or structure permitting the longitudinal movement of head 406 as described above. Head 406 may be slidably, radially, rotatably and/or otherwise movably mounted with the movable frame in any manner and by any mechanism or structure permitting the necessary movement of the head 406 as described above. Preferably, a plurality of bearings (not shown) is positioned in the moveable frame to facilitate the sliding movement of head 406. A proximity and location sensor (not shown) may be provided with head 406 to determine a current location of head 406 with respect to pipe 100.

Cutting system 404 may comprise a movement mechanism (not shown) or device capable of longitudinally moving head 406 longitudinally along transport system 402 and pipe 100 and rotationally about a surface of pipe 100 about its transverse axis. The movement mechanism may comprise a gear assembly (not shown) or another drive mechanism known to a person of skill in the art. Any gear assembly operatively connected with head 406 to longitudinally and or rotationally move head 406. In one embodiment, the gear assembly comprises a rack and worm gear assembly.

Cutting system 404 may have multiple heads 406, including different heads using different cutting systems (e.g. different water mixtures, plasma cutters, laser torches, etc.). Cutting system 404 may also have one or more additional cutting devices, such as a circular saw or blades (not shown). Such additional cutting devices (e.g. cutting saws) and heads may be independently moved in a manner about system 404 as described for head 406.

Once perforations 108 have been cut into pipe 100, the interior surface may be deburred. In a water jet system, laser or other beam-based cutting system, a need for deburring may be reduced.

Turning now to transport system 402, bed 414 provides a movable base to support pipe 100 as it is being cut. Bed 414 may be moved in a longitudinal direction (forwards and backwards) along the longitudinal axis of pipe 100. Bed 414 may also be moved in a lateral direction (left and right) along the traverse axis of pipe 100. Bed 414 may be canted up or down along its longitudinal axis and may further be canted left or right along its traverse plane. Support 416 is mounted on bed 414 and is shaped to receive and hold pipe 100 and to expose a surface of pipe 100 to head 406 as pipe 100 is being cut. Rollers 418 in support 416 allow pipe 100 to be rotated about its transverse plane (clockwise and counter-clockwise) to allow pipe 100 to be rotated about its traverse plane to expose different locations of pipe 100 to head 406 along a current transverse plane of pipe 100. Rollers 418 and support 416 provide structural support for holding pipe 100 and may comprise any suitable structure and material for providing such a structural framework for pipe 100 to bed 414. A clamping or securing system may be provided (not shown) to secure pipe 100 to bed 414.

Bed 414 and rollers 418 may be implemented in a gear assembly operatively connected with bed 414 to longitudinally and or rotationally move pipe 100 about cutting system 404. In one embodiment, the gear assembly comprises a rack and worm gear assembly. It will be seen that bed 414 may be moved in a longitudinal direction and/or in a lateral direction while rollers 418 rotate pipe 100. As such, there is a full range of movement for pipe 100 while head 406 is set at a given location. In addition, head 406 can also simultaneously be moved as previously noted to further position head 406 at specific locations and angles relative to the surface of pipe 100.

In operation, sacrificial pipe 420 may be inserted into part of pipe 100 as head 406 is releasing its stream 408 towards pipe 100 to ensure that only the target area of pipe 100 is actually cut by stream 408. Sacrificial pipe 420 effectively absorbs residual force from stream 408 after it has cut through top wall 106 of pipe 100. A holding and positioning system (not shown) for sacrificial pipe 420 may be provided with transport system 402 to selectively position pipe 420 inside pipe 100 and retract pipe 420 therefrom depending on whether head 406 is cutting pipe 100 or not. In one embodiment, the holding and positioning system comprises a rack and worm gear assembly.

An embodiment may also form cuts to pipe underwater or with pipe 100 being semi-submerged to help dissipate flow energy during the perforating process. A sacrificial pipe may or may not be needed for laser perforating.

System 400 may be used to hold pipes 100 having various OD and IDs. For example, most typical pipes may have an OD of between approximately 51 mm (2 inches) and 381 mm (15 inches), with a typical OD of between approximately 102 mm (4 inches) and 244.5 mm (9⅝ inches). A typical thickness for wall 106 may be between approximately 6.4 mm (0.25 inches) and 76.2 mm (3.0 inches) with a typical thickness of approximately 12.7 mm (0.5 inches). However, system 400 may be adapted to accommodate varying thicknesses for wall 106. System 400 has one or more power sources (not shown) for systems 402 and 404.

In an alternative embodiment a portable cutter system 404 has a simplified transport system 402 (or no transport system 402). In that embodiment, cutter system 404 has a frame that extends over pipe 100, which is securely mounted to a structure. System 404 is self-contained and has movement and alignment systems to move along pipe 100 (which remains stationary or mostly stationary) to position head 406 at appropriate locations as it cuts perforations 108 into pipe 100. As such, a portable system may be used to cut pipes 100 at a drilling site. A portable system may have a reduced number of flow heads for creating perforations and may be mounted on a mobile tractor trailer unit having a pipe rack through feed system mounted to the trailer.

FIG. 4B shows an exemplary orientation of head 406 about pipe 100 in system 400 to cut perforation 108 having an OD (i.e. at its major axis) that is smaller than its ID. It will be seen that head 406 is located offset from an axis of the lateral plane of pipe 100 (as shown by axis 114). Pipe 100 may be mounted to transport system 402 (not shown). It will also be seen that pipe 100 has been rotated. This orientation is a snapshot in time. As the conical shape of perforation 108 is scribed by stream 408, head 406 and pipe 100 will be simultaneously moved and rotated to position stream 408 properly about pipe 100. Sacrificial pipe 420 is not shown. Head 406 is mounted on a frame and can rotate about its local vertical axis and in a circular motion to create a circular perforation having a slope (in degrees) as designed for the conical perforation (either for a right cone or an oblique cone as shown in FIGS. 3A-3D). Pipe 100 shows perforation 108 b that has its opening 110 b (OD) that is larger than its opening 112 b (ID). For perforation 108 b a different orientation of pipe 100 with respect to head 406 is used to cut its profile.

FIG. 4C shows an alternative exemplary orientation of head 406 about pipe 100 in system 400 to cut perforation 108 having an OD that is smaller than its ID. Pipe 100 may be mounted to transport system 402 (not shown). It will be seen that head 406 is located along the diameter axis of pipe 100 (as shown by axis 114) and has its head rotated about the traverse axis of pipe 100 by 8 degrees (i.e. the offset in degrees between the OD and the ID, as described earlier). It will also be seen in this configuration, that pipe 100 is not rotated. This orientation is a snapshot in time. As the conical shape of perforation 108 is scribed by stream 408, head 406 and pipe 100 will be simultaneously moved and rotated to position stream 408 properly about pipe 100. Sacrificial pipe 420 is not shown.

Other perforations and slots may be formed using a combination of cutting devices. For example, an initial longitudinal slot may be made with a circular saw and its edges of its slot may be rounded with a water jet or laser.

In an alternative embodiment, system 400 may be configured so that head 406 is located in the interior of pipe 100 and scribes perforations 108 from interior surface 104 to exterior surface 102 by positioning head 406 to aim stream 408 away from the center of pipe 100. In such a configuration, a sacrificial pipe may not be needed.

Further details are now provided on different patterns for perforations 108. For example, in an embodiment, head 406 may be programmed to scribe a pattern that fully cuts out perforation 108 in pipe 100. In other embodiments, a perforated cut pattern may be provided. The exercised part from perforation 108 may be finally removed with a blunt force (applied from the outside of pipe 100 inwardly for perforation 108) after the perforated pattern is fully cut.

Other embodiments may provide differently sized and shaped perforations. Exemplary combinations are described below in FIGS. 5A-5E, where five additional exemplary different perforation patterns (compared to those show in FIG. 1) are shown.

FIG. 5A shows pipe 100 having a series of differently dimensioned perforations 108 a, 108 b and 108 c inscribed therein. Having differently dimensioned perforations (across their diameters or major axes) may facilitate filtering of heterogeneous materials (e.g. sand) along different sections of a well bore where pipe 100 is being inserted. FIG. 5A shows perforations 108 a, 108 b and 108 c being adjacent to each other, but in other configurations, pipe 100 may first have a length having perforations 108 a, then a second length having perforations 108 b and then another length having perforations 108 c. A mix of perforation diameters (OD and/or ID) may also be provided along a length of pipe 100, where there a majority of perforations (or where there is a least a significant percentage of perforations) having one size.

FIG. 5B shows pipe 100 having a series of differently sized perforations 108 a and 108 c and longitudinal keystone slot 118 inscribed therein. As noted in FIG. 4A, cutting system 404 may have a circular saw provided therein. As such, system 404 may make conical perforations 108 a and 108 c with a water jet using head 406 and keystone slot 118 using a circular saw (or other bladed instrument). Alternatively, a separate processing stage can be provided to cut keystone slots 118 into pipe 100 after head 406 has inscribed perforations 108 a and 108 c. Slots 118 may be oriented longitudinally, traverse or diagonally with the longitudinal axis of pipe 100. One or more of slots 118 may be located in proximity to one of perforations 108 in a general direction of flow of materials in pipe 100.

Some exemplary features of having a mix of conical perforations and keystone slots may include: faster and improved control of sand in heterogeneous reservoir sands from combined sand control specifications (where there are smaller conical perforations compared to blade slots and increased structure strength on a pipe liner and improved sand control due to conical perforations providing better arching of in situ sands around keystone slots. FIG. 5C shows pipe 100 having a series of differently sized perforations 108 a and 108 c and longitudinal keystone slot 118 inscribed therein similar to those shown in FIG. 5B, but each line is offset from each other (here about half the height of a perforation). In an embodiment, an existing longitudinal slot 118 may be recut to be conical, racetrack (a generally rectangular opening with rounded corners) or oval perforations by scribing a different ID or OD using system 400. For example, a large ID may be scribed using a cutting position for head 406 as shown in FIG. 4C, where the existing OD per opening 110 of an existing perforation is maintained, but a larger ID is cut, per opening 112. Slots 118 may be formed either by a cut or by scribing by system 400. The edges of slots 118 may be rounded. The interior dimension of slots 118 may be larger or smaller than the exterior dimension.

FIG. 5D shows pipe 100 having a series of perforations 108 formed therein where perforations 108 are inscribed on path shown by line 120 on pipe 100 that rotates along its surface as it progress along is length. As such, the pattern follows an arc around pipe 100, rather than a longitudinal line (as shown in FIG. 1) down pipe 100. As such, adjacent perforations are offset from a line of an expected direction of flow of materials in pipe 100. Following an arc may provide fairly complicated patterns for perforations in pipe 100 while simplifying programming steps for cutting same with system 400. For example, once the longitudinal and rotational movement parameters are set for pipe 100 (using for example transport system 402, FIG. 4A), head 406 (FIG. 4A) may not have to be moved or programmed as much and time to form perforations in pipe 100 may be reduced.

Other formations of perforations can be provided. FIG. 5E shows pipe 100 having an arrangement of perforations 108d that follows an orientation of a rotation of the pipe line (shown as lines 122), which may provide strength against torque forces of imparted on a liner during installation. Here, each perforation 108d resembles an “S”, but in different dimensions and orientations. A major axis for perforation 108d may run through its mid-point. The perforation may have any complex curvature form, but may resemble a hollow “S”, “Z”, “C”, “

”, “V”, “

”, “L”, “

”, “

”, “┘”, “┌”, “˜”, “\”, “▴”, “▾”, “

”, “

”, “▪”, “♦”, (or other symbols or shapes) or parts thereof in any orientation. It will be appreciated that various arrangements of perforation forms, perforation sizes, perforation width and perforation dimension may be provided to control sand in differing locations along the horizontal well bore to control sand, in situ particles or fluid flow. A major axis for such shapes may run through the shapes' mid-points and may reflect a longest dimension of the shapes.

In other embodiments, one or more perforations, slots and configurations shown in FIGS. 2 and 5A-5E may be combined in various combinations. For example, features of one or more of FIGS. 2 and 5A-5E may be combined in a same section of pipe 100 and/or may be provided sequentially along a length of pipe 100. Perforations shown if FIGS. 2 and 5A-5E may have differently dimensioned and shaped exterior openings 110 and interior openings 112 and may have offset centers (such as shown for perforation 108′ in FIGS. 3C and 3D).

Pipe 100 may be configured to have different densities and/or number of perforations 108 in its length depending on the target location of pipe 100 in a well bore. For example, if pipe 100 is meant to be located near the toe portion of the well bore, the density and/or number of perforations may be increased by a multiple compared to if pipe 100 is meant to be located nearer to the heel portion of the well bore.

It will be appreciated that the various forms, shapes, sizes and combinations of perforations described herein may be applied to any pipe, or pipe-like structure, of any composition having a wall and an inner and outer surface. Such perforations may be provided for such pipes deployed in various environments (e.g. in ground, above ground etc.) for various extraction and/or filtering operations. As noted, for a well bore, typically a liner may be provided with such perforation to provide effective flow of materials into the liner from outside of the liner, while filtering or screening particles of a certain size or greater from entering the liner. In other configurations, the liner may be provided with perforation to keep materials of a certain size that are being carried within the liner inside the liner while providing flow of smaller materials to the outside of the liner. In other embodiments, a liner with perforations described herein may be deployed to filter materials from a liquid, from particulates, from air, or from an environment having any combination of such materials.

As used herein, the wording “and/or” is intended to represent an inclusive-or. That is, “X and/or Y” is intended to mean X or Y or both.

In this disclosure, all measurements, dimensions, tolerances, operating ranges and thresholds are provided as exemplary and approximates value (for example, when the adjustment values is qualified with the word “approximately” or “about”), a range of values will be understood to be valid for that value. For example, for an adjustment value stated as an approximate value, a range of about 25% larger and 25% smaller than the stated value may be used. Thresholds, values, measurements and dimensions of features are illustrative of embodiments and are not limiting unless noted. Types of materials described are exemplary and not limiting. Purposes for pipes are as described exemplary and not limiting.

The present disclosure is defined by the claims appended hereto, with the foregoing description being merely illustrative of embodiments of the disclosure. Those of ordinary skill may envisage certain modifications to the foregoing embodiments which, although not explicitly discussed herein, do not depart from the scope of the disclosure, as defined by the appended claims. 

1. A pipe for a well bore for filtering materials entering the pipe, comprising: a wall having an exterior surface and an interior surface, the wall forming the pipe; and a perforation located in the wall, the perforation for receiving and screening the materials and forming an aperture in the wall from the exterior surface to the interior surface with a first opening on the exterior surface having a first dimension across a first major axis of the first opening and a second opening on the interior surface having a second dimension across a second major axis of the second opening, wherein the first opening is shaped to be either round, oval, elliptical or racetrack.
 2. The pipe for a well bore as claimed in claim 1, wherein: the first opening is round in shape; the second opening is round in shape; and the first major axis is smaller than the second major axis.
 3. The pipe for a well bore as claimed in claim 2, wherein: the perforation is a truncated right cone in shape.
 4. The pipe for a well bore as claimed in claim 2, wherein: the perforation is a truncated oblique cone in shape.
 5. The pipe for a well bore as claimed in claim 4, wherein: an axis for the truncated oblique cone is offset in a direction of expected flow of the materials in the pipe.
 6. The pipe for a well bore as claimed in claim 4, wherein: an axis for the truncated oblique cone is offset oblique to a direction of expected flow for the pipe.
 7. The pipe for a well bore as claimed in claim 1, wherein: the first opening is round in shape; the second opening is round in shape; and the first major axis is larger than the second major axis.
 8. The pipe for a well bore as claimed in claim 1, further comprising: a second perforation located in the wall, the second perforation forming a second aperture in the wall from the exterior surface to the interior surface with a third opening on the exterior surface having a third dimension across a third major axis of the third opening and a fourth opening on the interior surface having a fourth dimension across a fourth major axis of the fourth opening, wherein at least one of the third or fourth dimensions is different from the corresponding first or second dimensions.
 9. The pipe for a well bore as claimed in claim 8, wherein: the second perforation is located in a line of a direction of flow of the materials in the pipe with the perforation.
 10. The pipe for a well bore as claimed in claim 8, wherein: the second perforation is located in offset from a line of a direction of flow of the materials in the pipe with the perforation.
 11. The pipe for a well bore as claimed in claim 8, wherein: the third dimension of the second perforation is larger than the first dimension of the perforation.
 12. The pipe for a well bore as claimed in claim 8, wherein: the third dimension of the second perforation is smaller than the first dimension of the perforation.
 13. The pipe for a well bore as claimed in claim 1, further comprising: a slot located in the wall, the slot being in proximity to the perforation at a location in the pipe that is in a direction of flow of the materials in the pipe.
 14. The pipe for a well bore as claimed in claim 13, wherein: edges of an interior opening of the slot are rounded by a water jet.
 15. The pipe for a well bore as claimed in claim 1, wherein the wall is shaped in a cylinder.
 16. The pipe for a well bore as claimed in claim 1, wherein: the perforation is formed by a water jet applied to the exterior surface of the pipe; and a sacrificial pipe is placed in the interior of the pipe as the water jet forms the perforation. 